Method for forming tubular structures



Patented Sept.V 14, 1948 METHOD ron FoaMING rUBULAn STRUCTURES Andrew Joseph Paucek, Flushing, N. Y., assigner to Burndy Engineering Companmllnc., a c orporation of New York Application March 25,1'944, Serial No. 528,137

1 Claim.

My invention relates to a method and .tool forforming a tubular structure wherein a tube of material may have one end thereof formed into a predetermined shape.

Hitherto such .forming operations have been accomplished by expensive and labor-consuming methods with uncertain results.

The principal object ofv my invention is to provide a method and a novel tool to be used in conjunction therewith which will produce a reducing, neck forming, enlarging, closing, wall thickening, wall thinning or other shaping operation upon apiece of tubular stock, in a simple operation, at low cost,` in a relatively short period of time. and utilizing existing apparatus.

Other objects are to provide a tool for accomplishing the foregoing that may be continuously used despite the wearing action and the formation of high temperatures and pressures; to provide a tool which is capable of generating sufficiently `high temperatures in its operation to produce a plastic condition in the work at the point lwhere a change in form is desired; to provide a tool capable of forming the work to predetermined dimensions and within acceptable tolerances; and to provide a tool for forming tubular stock wherein the thickness of the formed wall may be controlled thereby.

I accomplish these and other objects and obtain my new results as will be apparent from the (cl. s-in)v the ends of tubes, and forming a bead about the formed end.

Fig. 11 is a sectional view taken in the plane I of II-II in Fig. 10.

device described in .the following specification,

particularly pointed out in the claim, and illustrated in the accompanying drawing, in which:

Fig. 1 is a semi-sectional side view of one form oi' my tool used for enlarging the ends of tubes.

Fig. 2 is-a sectional view through plane 2--2 of Fig. 1.

Fig. 3 is a sectional view taken through the plane 3-3 of Flg.1.

Fig. 4 is a semi-sectional side view of another form of my tool used for reducing the ends of tubes. t

Fig. 5 is a sectional View thereof, taken through 5 5 of Fig. 4.

Fig. 6 is a sectional view of a modied set of pressure pins for reversing the tube end inwardly.

Fig. 7 is an exploded view of'a modified form 'of tool for enlarging the ends of tubes, and trimming the ends thereof.

Fig. 8 is a similar view with tool inserted into the tube.

Fig. -9 is an end view ofthe tool, taken from 9-9 of Fig. 7.

' Fig. 10 is a side view of a tool, for enlarging Referring more particularly to the drawing, and especially to the tool illustrated in Figs. 1 to 3. reference numeral I0 designates an enlarging tool body, having an extending shank portion II for insertion into the gripping socket of a screw machine, drill press or other type of machine wherein the tool or work may be spun, relative to each other, in a manner known to the art, and therefore not shown.

At the other end of the tool Ill. a guide Itis formed having a diameter approximatey equal to the inside diameter of a tube which it is desired to have enlarged. Between the guide I2, and the body I0, the tube forming structure is shown. This consists of a longitudinally positioned metal insert I3, having an outer shape conforming to the inside shape of the junction of the `tube enlargement. In the modification shown in Figs. 1 to 3, the tool body I0 is of square stock, which may be of cold rolled steel. The four longitudinally formed corners have been removed and replaeedwith a hard material capable of resisting abrasion and wear, and of operating at high temperatures without damage thereto. Such a material is Stellite. These metal inserts I3 may be welded to the tool body I0, or otherwise suitably secured thereto, and partially extend into the guide I2. A

y As is evident from Fig. 3, the four hardened metal inserts come in contact withthe inside wall of the tube I4 at substantially minimum lines of Contact and by rotating the tube and vtool relative to each other, and simultaneously applying pressure to force the two together.A the wall I5 at the point where the metal inserts come in contact therewith is deformed to the initial shape of the tool until the deformed metal work hardens suiilciently to prevent further deformation of the meta-l and thereafter applying additional pressure causing the work hardened metal to be heated by frictionl to a point where the work hardened metal ofthe tube becomes annealed or plastic and expands under the pressure to further deform the annealed work hardened section to permit thc until the pressure on the two rotatingV parts is released.

The free spaces il are equal to or greater cirpressure intensities causing the work hardening i of the metal which results in preventing further deformation until the pressures cause the friction to develop suillcient heat to anneal the metal junction will give the maximum wall thickness at I4. Increasing the circumferential free spaces reduces ther wall thickness it is believed by causing the tool to work the metal toa greater degree and therefore thinning it. 4

For reducing the diameters of a tube, the tool illustrated in Figs. 4 and 5 may be used. Here the tool body is provided with shank 2l and a central bore 22, at the opposite end thereof. A plurality of longitudinally and cylindrically formed slots 23 are made in the wall 24 into which slots extremely hard pins 2l, are pressure fitted. The length of the pins is approximately equal to the depth of the bore 22, which permits a reduction of the diameter of work tube for an equal length. The slots 2l, in wall 24, permit the pins 25 to extend radially into the bore 22 so as to establish contact with the tube. 'I'he extending ends 28, of the pins are shaped to provide a gradual change in direction from the maximum diameteryfl, of tube, to the reduced diameter 2l.

The pins are preferably made of extremely hard, wear resistant material, such as Btellite which may be operated at high heat ranges without injury or softening.

In Fig. 6, I have shown an arrangement of pins which will produce an inwardly projecting tube end. This is accomplished by pressure fitting the U-shaped pins III into a socket 3| similar to slots 23 shown in Fig. 4. The tube 32 engages the ends 33 of the pins I0, and follows the U- shaped formation of the pins until the end 24 of the tube 32 assumes the inwardly projecting-V position as shown in Fig. 8.

If it is desired to close the end of the tube I2 entirely, the pins may be made U-shaped across the entire diameter as indicated by the dot and dash lines 3l of Fig. 6. 'I'he tube end will assume the position of the dot-dash lines 24.

Where it is desired to enlarge or reduce tubes of smaller diameters, a tool made entirely o hardened material may be used.

Such a tool is shown in Figs. 7, 8 and 9. Here a tool Il having a shank 4l has a plurality of longitudinally formed grooves 4'I positioned between the guide 42 and the body 4l. The grooves or free areas, create on each side thereof, an equivalent structure to the inserts I2 or pins 24, as shown in Fig. 9, with the contacting surfaces 42 like the pins and inserts. presenting areas of minimum contact to the inner surface of the Atube 44, so as to permit high speeds with suflicient heat generated to render the work hardened and friction heated area 4l of the tube in substantially a plastic or annealed condition. Here too, the rate of change of the controlled plastic portion from the narrow tube44 to the enlarged section 4l is accomplished by substantially reversed curves which facilitates the process. In

the tool shown the radially overhanging shoulderv 4l is provided, having longitudinally extending slots 41, into which the expanded end of the tube 4l will be forced. Edges 4l and 4l will trim the end of the tube as the tube and tool are rotated with reference to each other.

In Fig. l0. a tool is shown for causing a bead to be formed at the edge of the enlarged tube. The tool is made of the same type of wear resistant metal capable of operating at high temperatures caused by the enlarging neck Ul made up of longitudinally positioned teeth l2 extending from the guide pin I3, to the body I4. The enlarging neck- Il under the pressure applied between the tool and the tube as one rotates with respect to the other after work hardening. causes the work hardened section or area in contact with the enlarging neck to become plastic or substantially so, as the heat is generated, until the plastic metal conforms to the enlarging neck while the tool progressively renews the plastic zone to further deform the annealed work hardened section as the pressure is maintained to permit the tool to advance and work harden the metal of the stock in advance of the annealed work hardened section of the zone to form the desired length of the enlarged/ portion Bl. At this point the end 54 of the enlarged portion encounters a curved shoulder l1 in the junction between the teeth and the tube body which rolls the edge II to form a bead Il.

In all the foregoing constructions. I have effectively' provided a novel tool and a method of working tubular stock`to enlarge or reduce or otherwise conform or deform the stock to the shape of the tool until work hardened by rotating the tool and stock with respect to each other while applying sufficient pressure' therebetween to cause the heat generated at the work hardened junction point to create a plastic or annealed condition in the work hardened section or zone of the stock in contact therewith. The pressure additionally causes the stock to deform. work harden, anneal and conform to the tool while the work hardened stock is progressively heated, which permits thetool to move progressively on the tubular stock.

The characteristic feature of. the tool wherer it engages the stock is the multiplicity of free areas between points of contact `with the stock: the use of minimum areas of contact of wear resistant metal pressure elements; and the control of the free areas to increase or decrease the vwall thickness.

It may be noted that the slope of the reducing or enlarging neck is most effective where the ansire it understood that it is not confined to the particular forms or uses shown and described, the same being merely illustrative, and that the invention may be carrried out in other ways without departing from the spirit of my invention, and, therefore, I claim broadly the right to employ all equivalent instrumentalities coming 5 within the scope of the means of which, objects of my invention are attained, and new results accomplished, as it is obvious that the particular embodiments here .shown and described are only some of the many that can be employed to attain these objects and accomplish these results.

WhatI claim and desire to secure by Letters Patent, is as follows:

The method of shaping metallic tubular stock with a tool which consists in applying the tool to the stock at room temperature at a plurality of points around the end circumference of the stock appended claim, and lilyl with a plurality of free areas in between, the

points of contact having a total circumferential length less than the total circumferential length of the free areas and simultaneously applying pressure and rotating the tool and stock relatively to each other suillciently to deform the stock to the initial shape of the tool and to work harden the deformed metal of the stock suillciently to prevent further deformation of the metal, thereafter applying additional pressure to create sufllcient friction to cause the temperature of the work hardened metal to rise to the annealing point and make the work plastic to enable the tool to further deform the annealed work-hardened section to permit the tool to advance and work harden the metal of the stock in advance of the annealed Workhardened section, and continuing the process until th'e desired longitudinal deformation has been obtained.

' ANDREW JOSEPH PAUCEK.

REFERENCES CITED The following references are of record in the flle of this patent: 

